编辑“︁G418”︁（章节）

==作用機理及抗性機理==
G418是一種特殊的[[抗生素]]。G418既可以殺死[[真核細胞]]，也可以殺死[[原核細胞]]。G418的作用機理是通過與[[核糖體|80S核糖體]]（真核細胞）或70S核糖體（原核細胞）結合，進而阻止蛋白轉譯過程中的延長過程，使合成中的多肽鏈合成中止。最終，細胞會因爲缺乏必要的蛋白而死亡<ref>{{cite web|url=https://www.promega.com/-/media/files/resources/technical-references/antibiotic-mode-of-action.pdf|title=Antibiotics: Mode of Action and Mechanism of Resistance.|publisher=Promega|accessdate=2017-11-29|archive-date=2017-12-01|archive-url=https://web.archive.org/web/20171201032931/https://www.promega.com/-/media/files/resources/technical-references/antibiotic-mode-of-action.pdf|dead-url=no}}</ref><ref>{{cite web|url=http://www.invivogen.com/PDF/G418_TDS.pdf|title=G418 manual|publisher=invivogen|accessdate=2017-11-29|archive-date=2018-01-27|archive-url=https://web.archive.org/web/20180127124021/http://www.invivogen.com/PDF/G418_TDS.pdf|dead-url=no}}</ref>。基於G418的作用機理，對蛋白質需求較高的細胞，如分裂中的細胞，會比對蛋白質需求相對較少的細胞更快被G418殺死<ref>{{cite web|url=http://www.invivogen.com/g418|title=G418 introduction|publisher=invivogene|accessdate=2017-11-29|archive-date=2017-11-19|archive-url=https://web.archive.org/web/20171119060044/http://www.invivogen.com/g418|dead-url=no}}</ref>。新黴素抗性基因''neo''可以使細胞在含有G418的培養基中存活。''neo''基因抵抗G418的機理在於，neo基因能編碼一種{{link-en|氨基糖苷3'磷酸转移酶|aminoglycoside-3’-phosphotransferase}}。該酶可使G418磷酸化，減小其與核糖體的親和力，達到讓G418失效的作用<ref name="Kotra 2000">{{cite journal|title=Aminoglycosides: Perspectives on Mechanisms of Action and Resistance and Strategies to Counter Resistance |url=https://archive.org/details/sim_antimicrobial-agents-and-chemotherapy_2000-12_44_12/page/3249 |authors=Kotra, LP, Haddad J, Mobashery, S|PMID= 11083623|year=2000|PMC=90188|journal=Antimicrobial Agents and Chemotherapy|volume=44|issue=12|pages=3249–56|doi=10.1128/aac.44.12.3249-3256.2000}}</ref>。